Apparatus for straightening long metal workpieces

ABSTRACT

A metal tube straightening machine having several longitudinally spaced groups of rolls with each group comprising a top and bottom rolls. The workpiece is laterally placed into the apparatus between the rolls and axially advanced, between the rolls, only for a distance approximating the distance between two contiguous straightening rolls. A hydraulic pressure responsive arrangement and gearing mechanism is provided to control the movement of the top roll.

United States Patent [191 Lorenz et al.

[451 Oct. 14, 1975 APPARATUS FOR STRAIGHTENING LONG METAL WORKPIECES [75] Inventors: Horst Lorenz, Solingen; Rolf Eckhard Koch, Witzhelden; both of Germany [73] Assignee: Th. Kieserling & Albrecht, Solingen,

Germany 22 Filed: June 10, 1974 21 Appl. No.: 477,830

3,533,257 lO/l97O Aldred 72/99 FOREIGN PATENTS OR APPLICATIONS 725,630 9/1942 Germany 72/99 Primary Examiner-Lowell A. Larson Attorney, Agent, or Firm-Edward E. Sachs [57 ABSTRACT A metal tube straightening machine having several longitudinally spaced groups of rolls with each group comprising a top and bottom rolls. The workpiece is laterally placed into the apparatus between the rolls and axially advanced, between the rolls, only for a distance approximating the distance between two contiguous straightening rolls. A hydraulic pressure responsive arrangement and gearing mechanism is provided to control the movement of the top roll.

8 Claims, 7 Drawing Figures US. Patent 0a. 14, 1975 Sheet 2 0f 3 3,911,708

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AV AV AV AV APPARATUS FOR STRAIGI-ITENING LONG METAL WORKPIECES The invention relates generally to a metal working apparatus and. more particularly, to an apparatus for straightening long metal workpieces, such as rods or tubes, of substantially circular cross section. The apparatus has driven hyperbolic rolls to which the workpieces are fed transverse to the length of the workpiece.

Modern continuous rolling mill trains for the production of tubing have and require a high output capacity.

Therefore, the speed at which the tubes are discharged from the stretch-reducing rolling mill is quite substantial. After being cooled, the tubes are checked for defects by non-destructive test methods, and are then cut into commercial lengths. In order to minimize the number of required test and cut-off devices, the lengths of tubing, which may be up to 160 m (meter) in length, arriving from the cooling bed, are cut to lengths of between and m. Modern tube or rod cooling beds are designed to pre-straighten the tubes as they pass along the beds. However, experience has shown that tubes thus straightened are not sufficiently straight to allow sections thereof to be properly tested by nondestructive testing devices. For that purpose, it is essential that the tubes pass, as nearly coaxially as possible, through the coils of the testing devices. It is economically desirable to keep the number of testing devices and cut-off units at a minimum. This is only possible if the tubes arriving at the testing station do not exceed a certain length. The tubes or rods arriving from the cooling bed are therefore cut into sections of about 25 m in length.

The straightening of tube sections of this length presents certain problems when this work step is to be accomplished on conventional straightening machines in which the tubes move only axially during the straightening process. Indeed, it is virtually impossible to straighten the tubes to the desired accuracy. On the other hand, if straightening machines having hyperbolic rolls are used, the tubes can be straightened with sufficient accuracy, but the output capacity of such a machine is not high enough to allow these machines to be used for this purpose unless additional test and cutoff equipment is made available, since the work cycle of the cooling-bed and the cut-off machine are synchronized with the output of the rolling mill.

It is therefore an object of the present invention to provide a straightening machine having hyperbolic rolls with which tubes or rods of about 25 m in length can be rapidly straightened with a sufficient degree of accuracy to permit the tubes to be passed coaxially through the coils of the non-destructive testing device.

It is a further object of the present invention to provide a straightening machine which obviates or significantly reduces the need for a large amount of the space normally required for the tube-feeding and removing equipment.

It is another object of the present invention to provide a straightening machine wherein the straightening section itself and the time to straighten long rods or tubes is considerably reduced. If desired, all of the straightening rolls may be arranged ina common housing.

An aspect of the present invention resides in providing a straightening machine for long metal workpieces of substantially circular cross section in which the machine or apparatus utilizes driven hyperbolic rolls. The machine is adapted for the workpieces to be fed at right angles to the length of the workpieces and includes several groups of straightening rolls, with each group constituting a bending triangle or straigntening station and being arranged in a housing, the number and spacing thereof being such that the entire length of the workpiece placed between the straightening rolls, can be clamped by the said straightening rolls, except for a length corresponding approximately to the distance between two contiguous groups of straightening rolls.

To facilitate the placing of the tubes laterally between the straigntening rolls, there is provided, as other aspects of this invention, in a conventional manner, that each top roll of the groups of straightening rolls is connected to a piston rod of a double-acting piston, with the end of the rod remote from the roll passing through the cover of the piston cylinder and being formed with a threaded stub. The external thread on each stub engages the corresponding internal thread of an axially adjustable gearwheel. All of the top rolls can thus be raised and lowered rapidly out of and into their operative positions, in order to place the workpieces between the rolls, or to place them on a roller table after they have been straightened.

In the prior art a straightening machine using hyperbolic rolls is already known, in which the top rolls are connected to pistons. The top rolls located at the inlet and outlet end are elastically supported in order to make it possible to straighten bars or tubes having a non-circular or out-of-round cross section. The front end of a workpiece introduced laterally from a grid is clamped between the inlet rolls by lowering the top roll. The workpiece is then driven forward and is straightened as it passes through the groups of rolls.

Long and heavy rods cannot be straightened in this manner because the straightening rolls located at the inlet end, which also act as entry rolls, cannot provide the necessary feeding and rotating movements without creating slippage between the rolls and the workpiece. This slippage causes the rolls to wear. It is totally impossible to feed and straighten long tubes in this manner because the forward end of the tube would be squeezed and twisted. Moreover, in straightening long tubes, inlet and outlet troughs of suitable length must be provided, for instance see West German Pat. No. 835,825.

In a straightening machine of this kind, the enclosed inlet trough could be replaced by a lead-in device, as shown for example in German Pat. No. 725,630. This device comprises several pairs of hyperbolic rolls, one

IN THE DRAWINGS FIG. 1 is a side elevational view of the straightening apparatus;

FIG. 2 is a plan view of the apparatus shown in FIG.

FIG. 3 is a view generally similar to FIG. 2 but in diagrammatic form showing the feeding, straightening and removing of the workpiece;

FIG. 4 is an enlarged elevational view of a group of rolls within a common housing;

FIG. 5 is a sectional view taken along line \/V of FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 4; and

FIG. 7 is an elevational view of the feeding device for transverse and axial transportation of the workpieces to be straightened.

Referring now to FIGS. 1 and 4 there are shown a plurality of groups of rolls comprising bottom rolls 1 and 2 and top roll 3 with each group being located in a separate C-shaped housing 4. Each top roll is driven by a motor 6 through a connecting cardan shaft 5. The bottom rolls 1 and 2 are individually, rotatably, supported by a frame 7 and the top rolls are rotatably suspended from a frame 12. Each bottom roll 1,2 is secured to a sleeve 8, see FIG. 5, which in turn is mounted about a threaded shaft 9 which can be rotated clockwise or counter-clockwise by a worm drive 10,11 connecting to the lower end of the shaft 9 for the purpose of suitably adjusting the operating positions of the bottom rolls.

All of the worm drives 10,11 and consequently shafts 9 are driven by a motor, not shown. Each frame 12 supporting a top roll 3, is suspended from a piston rod 13 of a doubleacting piston 14, with the end of the rod remote from the roll projecting through the cover of a cylinder 15 and being formed as a threaded stub 16. The external thread of stub 16 engages a corresponding internal thread of an axially adjustable gearwheel 18 disposed in the upper portion of the housing 4.

The axial adjustment of gearwheel 18 is effected by a pinion 19 engaging the external teeth 20 of gearwheel 18, and by bevel gears 21,22 driven by a motor, not shown, through a shaft 23. The pinion 19 and the bevel gears are mounted on journals 24 in housing 4. The rotation of shaft 23 alters the position of gearwheel 18 in relation to threaded stub 16, whereby the operative po sition of top roll 3 can be adjusted.

The rolls are secured in their operative positions as long as a fluid pressure medium passes through bore 25 to a cylinder 26 and acts upon piston 14.

In order to lift workpieces 27 from a feed grid 28 and to place the workpiece between the straightening rolls, conventional oscillating racks 29 are employed, see FIG. 7. After the workpiece has been straightened, the oscillating racks place the workpieces on a roller table provided with a driven roll 30 in each housing 4. A common drive shaft 31 is provided for all of the racks from a motor, not shown. The feed grid 28 holds the workpieces with their longitudinal axis parallel to the length of the straightening apparatus.

The operation of the apparatus proceeds as follows:

When a fluid pressure medium is initially fed through bores 32 to cylinders 26, the pistons 14 are caused to move upwardly. The fluid pressure expelled by pistons 14 can flow back to a reservoir through bores 25 and conduits, not shown. The top rolls 3 are then sufficiently remote from the bottom rolls that a workpiece lifted by oscillating racks 29 from grid 28, for example a tube 27, may be placed between the straightening rolls. Thus, except for section a which corresponds ap proximately to the distance b, see FIG. 3, between two contiguous groups of straightening rolls, the remaining length of the tube can be held by the straightening rolls after piston 14 has been actuated by the fluid pressure.

Upon activation of drives 6 of top rolls 3, the tube is advanced only by an amount corresponding approximately to length b of the pipe, and is thereby straightened. The rolls 3 are then raised again in the manner described above, and the drive to the oscillating racks 29 is switched on. As a result, the straightened tube is lifted off bottom rolls 2 and placed on rolls 30 which transport it, for example, to an apparatus, not shown, for non-destructive testing. To facilitate the handling of the workpieces the apparatus is provided at its ends and between the housings 4 with guide means 33, see FIG. 1.

The workpiece thus need be moved axially only over a part of its length of the operating process. Consequently, the elimination of additional forward or axial movement to straighten long tubes has considerably lessened the time element than heretofore possible. Although the overall length of the straightening apparatus is greater than that of known straightening machines, this is not to be regarded as a disadvantage, since the long troughs for feeding the workpieces and removing them are no longer required.

The use of the straightening apparatus according to the above described invention is obviously not restricted to the straightening of long tubes; it may also be employed to straighten long rods, shafts and the like. The number of the straightening rolls and the arrangement thereof relative to each other can be varied to suit conditions. Moreover, only individual rolls or all of the straightening rolls may be driven.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What we claim is:

1. An apparatus for straightening long metal work pieces of substantially circular cross-section, comprising:

housing means;

at least several groups of hyperbolic rolls within said housing means, each group constituting a bending triangle and being axially spaced from the next adjacent group, the number and spacing of the groups being such that the entire length of the workpiece is clampable by said rolls except for a length corre- .sponding approximately to the distance between two contiguous groups of rolls, the construction and arrangement of the group of rolls being effective to receive the workpiece in a direction transverse to its length, and with each group straightening only a specific length of the workpiece, said length approximating said distance between said two contiguous groups, whereby said length constitutes only a fraction of the total length of the workpiece;

and drive means connecting to said rolls for driving one or more rolls of each group.

2. An apparatus according to claim 1, wherein each said group of rolls comprises a top roll and two bottom rolls.

3. An apparatus according to claim 2, wherein said drive means includes hydraulic means controlling the vertical movement of the top roll. I i

4. An apparatus according to claim 3, wherein said drive means includes gearing means controlling the rotational movement of the top roll.

5. An apparatus according to claim 4, wherein said drive means includes a frame connecting to and suspending said top roll, a double acting piston means having a piston rod secured to said frame.

each group of rolls is arranged in an individual housing. 

1. An apparatus for straightening long metal workpieces of substantially circular cross-section, comprising: housing means; at least several groups of hyperbolic rolls within said housing means, each group constituting a bending triangle and being axially spaced from the next adjacent group, the number and spacing of the groups being such that the entire length of the workpiece is clampable by said rolls except for a length corresponding approximately to the distance between two contiguous groups of rolls, the construction and arrangement of the group of rolls being effective to receive the workpiece in a direction transverse to its length, and with each group straightening only a specific length of the workpiece, said length approximating said distance between said two contiguous groups, whereby said length constitutes only a fraction of the total length of the workpiece; and drive means connecting to said rolls for driving one or more rolls of each group.
 2. An apparatus according to claim 1, wherein each said group of rolls comprises a top roll and two bottom rolls.
 3. An apparatus according to claim 2, wherein said drive means includes hydraulic means controlling the vertical movement of the top roll.
 4. An apparatus according to claim 3, wherein said drive means includes gearing means controlling the rotational movement of the top roll.
 5. An apparatus according to claim 4, wherein said drive means includes a frame connecting to and suspending said top roll, a double acting piston means having a piston rod secured to said frame.
 6. An apparatus according to claim 5, wherein said gearing means connects to said rod at the end opposite to the location of said frame.
 7. An apparatus according to claim 6, wherein said gearing means comprises a cylinder rigidly connected to said rod and provided with outer gear teeth; and driven gears connecting to said cylinder in axially relatively movable relation.
 8. An apparatus according to claim 1, wherein said housing means comprises a plurality of housings and each group of rolls is arranged in an individual housing. 